1. Field of the Invention
The present invention relates to a novel optically active diphosphine compound, an intermediate for preparing the same, a transition metal complex having the same diphosphine compound as a ligand and a transition metal catalyst useful for a variety of asymmetric synthetic reactions.
2. Description of the Related art
There have hitherto been many reports on transition metal complexes which can be utilized for asymmetric syntheses such as asymmetric hydrogenation reactions, asymmetric isomerization reactions, asymmetric hydrosilylation reactions and the like. Inter alia, complexes in which transition metal complexes such as ruthenium, rhodium, iridium, palladium and the like are coordinated with an optically active tertiary phosphine compound have potent performance as a catalyst for an asymmetric reaction.
In order to further enhance performance, many phosphine compounds having various structures have hitherto been developed (Kagakusosetsu 32, edit. by Nippon Chemistry Society, "Chemistry of Organometallic Complexes", 237-238 (1982); "Asymmetric Catalysis in Organic Synthesis", Ryoji Noyori, A Wiley-Interscience Publication).
Inter alia, 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl (hereinafter referred to "BINAP") is one of the excellent optically active phosphines, and a rhodium complex having the BINAP as a ligand (JP-A 55-61973) and a ruthenium complex (JP-A 61-63690) have been previously reported.
Further, it has been reported that a rhodium complex (JP-A No. 60-199898) and a ruthenium complex (JP-A 61-63690) having 2,2'-bis(di-(p-tolyl)phosphino)-1,1'-binaphthyl (hereinafter referred to as "p-TolBINAP") as a ligand give better results in an asymmetric isomerization reaction. Further, it has been reported in JP-A No. 3-255090 that a ruthenium complex of 2,2'-bis(di-(3,5-dialkylphenyl)phosphino)-1,1'-binaphthyl gives better results in a reaction for the asymmetric hydrogenation of .beta.-ketoesters.
However, selectivities (diastereoselectivity, enantioselectivity) and catalytic activity are not sufficient depending upon an objective reaction and reaction substrate and, thus, improvement in a catalyst is occasionally demanded.